1. Technical Field
The present invention relates to image forming apparatuses.
2. Related Art
Image forming apparatuses such as a laser beam printer have been well-known. Such image forming apparatuses are furnished with, for example, a developer moving element which moves developer by rotating with the developer being borne thereon in order to transfer the developer onto a medium, and a collector for collecting the developer which has not been transferred onto the medium and remains on the developer moving element.
The above-mentioned collector is furnished with a scraper blade and the scraper blade abuts against the developer moving element to scrape the developer on the developer moving element (the developer which moves with the rotation of the developer moving element), in order to collect the developer which remains on the developer moving element. In addition, the collector is furnished with a sealing member, which contacts the developer moving element at a contacting section to prevent the developer scraped by the scraper blade from spilling outside the collector. Further, the scraper blade and the sealing member are structured such that they can contact with and separate from the developer moving element. More specifically, the scraper blade is movable between an abutting position and a non-abutting position and the sealing member is movable between a contact position and a non-contact position.
Now, when either of the scraper blade and the sealing member moves (contacts and separates), airflow occurs in the collector which moves the developer in the collector, and it may cause a problem that the developer is spilled from between the separated scraper blade and developer moving element or from between the separated sealing member and developer moving element. In order to resolve such a problem, there are cases where the image forming apparatuses are furnished with a ventilation opening for moving air in the collector outside the collector and a valve for adjusting an amount of air passing through the ventilation opening. In such a case, the ventilation opening moves air in the collector outside the collector to lower air pressure in the collector, and thus, serves to appropriately prevent developer from spilling from between the separated scraper blade and developer moving element or from between the separated sealing member and developer moving element. And, the valve serves to adjust air pressure in the collector depending on a degree of occurrence of the airflow. In heretofore image forming apparatuses, in a normal state in which the scraper blade abuts against the developer moving element and the sealing member contacts the developer moving element, the valve closes the ventilation opening, and thus air cannot pass through the ventilation opening. Besides, when either one of the scraper blade and the sealing member, whichever separates earlier from the developer moving element, starts separating therefrom, the above-mentioned condition remains maintained. In such a case, when the member starting separating earlier starts separating, high air pressure in the collector causes a problem that the developer is spilled from between the member and the developer moving element. Therefore, there is a demand for an image forming apparatus which enables to appropriately prevent developer from spilling.
When either of the scraper blade and the sealing member moves (contacts and separates), the volume of the collector (for example, the volume of a section surrounded by a housing of the collector, the scraper blade, the sealing member, a member for supporting the scraper blade, and a member for supporting the sealing member) changes. This change of the volume causes airflow in the collector and movement of developer in the collector by that airflow causes a problem that developer is spilled from between the separated scraper blade and developer moving element. The above-mentioned ventilation opening is for resolving the problem, and lowering air pressure in the collector by moving air in the collector outside the collector prevents appropriately the developer from spilling from between the separated scraper blade and developer moving element. Now then, some of the above-mentioned image forming apparatuses are furnished with a valve for adjusting an amount of air passing through the ventilation opening. It is desirable to adjust the amount of the air with the valve, to minimize an amount of the developer spilled from between the separated scraper blade and developer moving element. In short, there is a demand for an image forming apparatus which enables to appropriately prevent developer from spilling.
Further, the collector is furnished with a container for containing toner, and the container contains developer which has not been transferred onto a medium and remains on the developer moving element and which is collected by the collector. If the collector is furnished with a ventilation opening, there are cases in which, when air in a containing chamber moves outside the containing chamber through the ventilation opening, developer in the containing chamber also moves outside the containing chamber passing through the ventilation opening. In such a case, the developer moving outside the containing chamber through the ventilation opening may diffuse. Therefore, there is a demand for an image forming apparatus which enables to prevent diffusion of developer passing through a ventilation opening.
Further, since there are cases in which, when the collector has the ventilation opening, the developer in the collector passes through the ventilation opening to spill outside the collector, a filter is attached to the ventilation opening in some of the above-mentioned image forming apparatuses in order to prevent the developer in the collector from spilling outside the collector passing through the ventilation opening. Thus, since the developer passing through the ventilation opening adheres to the filter, it is possible to prevent the developer from spilling outside the collector. However, if a large amount of the developer in the collector adheres to the filter, the filter may become clogged with the developer. Then, when the filter becomes clogged with the developer, air in the collector cannot appropriately move outside the collector. Therefore, there is a demand for an image forming apparatus which enables to prevent a filter from being clogged with developer.
Note that JP-A-2004-61858 and JP-A-2004-157285 are examples of a related art.